I like my idea with range and probabilities. I thought about it. Both can be easyly modified.
- *0.5 for not concentrating on searching for illusion
- *0.5 for moving
- *1.5 for known topic. (A wizard will discover errors in a false wizards tower. An engeneer will discover errors in a false bridge)
Range Modifiers: The effort/mana the wizard used to create the illusion.
The invisible wall is a bad idea i think. A hidden city is also nonsense - even a blind spy can reveal it. It is difficult to hide something, where there are lots of people.
Cookbook of how to create a invisble city wall:
Step 1) Paint the wall in green color.
Who will not discover: Google Maps
Who will discover: Anyone within range of 20 km
Step 2) Paint Buildings on it.
Who will not discover: One eyed monster, because of lacking 3-dimensional view. Cylops, old seaman.
Who will discover: Anyone within range of 2 km
Step 3) Ensure the light will cross the wall.
Who will discover: Anyone within range of 500 m, because a line of grass is missing.
Step 4) Add grass at the bottom of the wall
Who will discover: Anyone who recognizes, that everything enters the city on the roads, nowhere else.
Step 5) Add false liveforms. False children playing soccer through the wall. False rabbits. Guards who force everyone to use the roads.
Who will discover: Anyone who recognizes, that the children should go to sleep or that bunnies are not awake at nght.
Step 6) At night: Change the rabbits to wolfs.
Who will discover: Anyone who recognizes, that ....